1. Field of the Invention
The present invention relates to a coffee machine with a housing, control and heating elements to heat up and supply fresh water to a brewing device, which comprises a brewing cylinder and two pistons, the brewing cylinder being drivable with a motor via a drive spindle and moveable in relation to the pistons.
2. Description of the Related
To prepare coffee with automatic coffee machines the so-called pressure brewing process is often used today. With this process hot water is conveyed under pressure through coffee powder present in a brewing chamber. The present invention relates in particular to coffee machines working according to this pressure brewing process. Many of them are already well-known on the market. Depending upon area of application, for example in households or in restaurant businesses, these known coffee machines differ in their construction especially with respect to robustness, flexibility in the running of the process, ease in servicing, cleaning and maintenance.
It is of common knowledge that in all coffee machines working according to the pressure brewing process, parts which come into contact with coffee powder and/or with the prepared drink are subjected to a certain soiling and have to be cleaned periodically. The cleaning of such parts varies in expense and time intensity from machine type to machine type. Depending upon the construction of a machine, the design of individual parts is more or less complicated with respect to maintenance or repairs.
In the German unexamined and published patent application DE 29 45 360, an automatic coffee machine is disclosed which works according to the pressure brewing process in which maintenance is facilitated in that the important elements of the coffee machine are housed in a kind of drawer which can be pulled out of the latter. In the housing of the coffee machine itself only a water tank and an outlet to provide the electrical connection between housing and drawer remain as securely installed elements. It follows from the specification of the German published application in connection with the drawings that, among other things, electrical, electromechanical as well as purely mechanical parts are housed in the drawer or in the module. One can say that the drawer contains all important elements and components of the coffee machine. These elements and components will be more easily accessible, especially for maintenance and repairs, than other embodiments of these types of coffee machines. For the periodic cleaning of the coffee-carrying elements, however, the brewing device as a component, for example, has to be to be dismounted or removed from the drawer each time, in that first the electrical and hydraulic connecting lines are disconnected and afterwards the brewing device itself removed by unscrewing the attachment screws. Such a procedure is disadvantageous for a process which is to be carried out periodically. Furthermore in the drawer there is a high risk of electrification due to the common arrangement of parts carrying electrical current and parts coming into contact with water.
In the European patent specification EP 0 154 206, a device is disclosed for preparation of hot drinks, especially coffee, in which a subassembly holder, removable from the device, is foreseen comprising all the parts exposed to soiling from coffee powder or from the prepared drink. This facilitates handling when cleaning the device in that only the subassembly holder has to be taken from the device. Since all the other parts are mounted securely in the coffee machine, a decisive advantage for cleaning purposes can no doubt be achieved through the design chosen, but not for servicing and repairs, however. Design of the other parts may not be necessarily easy. A control of the function of the coffee machine is only possible with the subassembly holder integrated or installed.